The Carpathian Disjunction

Norway spruce is naturally absent in the lower Beskid Mts (Beskid Niski), the lowest range of the western Carpathians and in the Pogorze Dynowskie and Pogorze Rzeszowskie regions in Poland for a distance of about 60 km. The lack of Norway spruce in these regions was described in the latter half of the 19th century (RIVOLI 1884; BRODOWICZ 1888; REHMAN 1895). This disjunction was depicted cartographically by WIERDAK (1927b) and subsequently adopted on the map of Norway spruce distribution in central Europe (KULCZYNSKI and WIERDAK 1928; SZAFER 1937). The lack of the spruce in the lower Beskids was explained by a lack of suitable climatic conditions. The hot and dry southerly winds were considered the main factor (RIVOLI 1884; REHMAN 1895). The occurrence of natural Norway spruce stands in the Bieszczady Mts on aspects and topographic positions shielded from the southerly winds appears to confirm this notion (ZARZYCKI 1963).

A natural origin of the Carpathian disjunction of Norway spruce has been supported by the observations of greatly reduced frequencies of pollen found in the peat bogs from the region (RALSKA-JASIEWICZOWA1983; RYBNi£:KOVA and RYBNiEEK 1988; see also Fig. 5.2), as well as in the variation of contemporary and sub-fossil cones of regional Norway spruce populations (MEZERA 1939; HOLUBCIK 1969b; STASZKIEWICZ 1966, 1967, 1976). Nevertheless, it should be mentioned, that in the early Holocene the populations of the western and eastern Carpathians were in contact with each other. The high frequency of the cone variety acuminata that is characteristic of the eastern Carpathians in the Tatras (western Carpathians) appears to support this opinion (Mezera 1939; STASZKIEWICZ 1976). Recent palynological studies also concur (SRODON 1990).

The contemporary distribution of Picea abies indicates an absence of the species in the lowest parts of the western Carpathians and associated submontane regions. These regions were covered with forests with a high abundance of Norway spruce in the Holcene about 5000 years ago. Subsequently, this forest type was largely replaced by broad-leaved forests (SRODON 1990). In the higher mountain ranges, Norway spruce has colonized the upper elevations and forms the contemporary high-elevation forest type present in this region. The shortage of this habitat in the lower portions of the western Carpathians is likely one reason that P. abies survived there only in sparse populations on the northern slopes, along riparian zones, and on landslides. Many remnant stands were eliminated by human activities in historical times

(SRODON 1990).

0 0

Post a comment